An inverted wheel type moving body is typically controlled to travel in such a manner that the position of the center of mass of the body is constantly corrected to maintain the stable state by driving right and left driving wheels. In such a moving body, sudden stop or sudden acceleration may cause overturning of the moving body. A moving body equipped with sub wheels in order to prevent such an overturning during the travelling is disclosed (patent documents 1 and 2).
For example, according to a vehicle in the patent document 1, sub wheels are arranged in a front-back direction of drive wheels. The sub wheels are provided in end parts of struts extended and retracted by actuators. Upon detection of the overturning by a detector that detects a moment, the strut is deployed by the actuator to bring the sub wheel contact with the ground.    [Patent Document 1] Japanese Patent Translation Publication No. 2000-514680    [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2006-247802